Lead screw adjusting means



Feb. ll, 1941.

A. E; DRlssNER LEADY SCREW ADJUSTING MEANS 2 Sheets-Sheet 1 Filed Feb. 23, 1938 lig Feb. l1, 1941. A. E. DRlsSNER LEAD SCREW ADJUSTING MEANS Filed Feb. 23,'1958 2 Sheets-Sheet 2 IIIHUVlILIII llpl Patented Feb. 1l,l 1941 PATENT oFFlce 2.23am c Laan scnaw Anrusrmcnmnus Alfred E. Drissner, Cleveland, Ohio, .,f

The National Acme Company, Cl

a corporation of Ohio orl to Ohio,

applicants Fen-um za, 193s, serial N. 192,017

ltillaims.

This invention relates to lead screws used in various types of machines to guide and'control the movement of the slide carrying the threading or similar tools and has,for its principal object the provision oi means for automatically adjusting the lead screw in a simple, efficient and inexpensive manner.

Heretofore, in threading tools and the like, wherein a lead screw was used for feeding the tool or the'work, the accuracy of the work depended upon the accuracy' with which the lead screw was cut so that it was essential in grinding a lead screw that it be 100% perfect or errors would result in the thread produced on the work.

In some cases, due to theheat of the work during the threading, even though a lead screw might be accurate, an error would result in the work due to the change in temperature from the beginning to the end of the work.- It is, therefore, one of the objects of this invention to provide means for adjusting the lead screw for ahy inaccuracies due either to incorrectness in the grinding of the lead screw or to compensate for the expansion of the work due to heat during the cutting operation, which adjustment will be gradual Aand 'effective over a particular portion or the entire work as desired.

Other objects and advantages will appear in the following description.

In the drawings accompanying and forming a part of this speciiication, Fig. l is a plan view illustrating the lead screw adjustment controlling means in section.

Fig. 2 is a sectional view taken on the line 2-2 of Fig. 1.

Fig. 3 is an enlarged sectional view of one end oi the lead screw and its adjusting means.

Fig. 4 is a plan view of the adjustment controlling means, and- Fig. 5 is a similar view illustrating one form of adjustment of the controlling means.

Similar characters of reference indicate cor.

responding partsln' the-several views.

Before explaining in detail the present -improvement and mode of operation thereof, desire to have it understood that the invention is not limited to the details of construction and Ordinarily, when a lead screw is used in the threading of a bolt or nut where accuracy is required, it ish customary to take the threaded article and place it in a projection machine to enlarge the thread perhaps 50 to lotlmes soy as to permit inspection of the exact lead of that screw and if found to be slightly oir which, in many cases is perhaps a matter of but -.001",v 5 since the lead screw cannot be corrected after installation on the machine because,` ythe, thread n -of the lead screw is xed to the body of the shaft thus forming a single unit and it is, therefore, necessary to remove the lead screw torethread or regrind it.

Furthermore, a coupling which is used to con-V nect pipes hasta ilt very accurately in the thread to eliminate leaks under great pressure. For instance, when cutting a diameter of six inches, 15 the length of the thread is approximately three to three and a half inches. The thread is-ta `pered and, therefore, when the coupling isplaced in the machine to be threaded. thecoupling 'is cold and when the threading tool cuts the thread 2,

in the coupling,'it will heat the coupling due to the cutting speed oi' the tool so that bythe time the full length of the .thread is cut,A the heat of the coupling may be increased from forty to one hundred and twenty degrees. Therefore, it .25 is necessary to take into consideration thecoemcient of 4expansion of the metal to be operated upon in cutting a lead screw since one that might produce perfectly accurate results with one maav terial might produce incorrectv results with an- 30 other. i

It is with this in mind thatthe present invention was devised andit will be seen from the following that the foregoing difculties are eliminated. 35

In the present instance, the lead screw '2 of the machine is fixed within a suitable adjusting nut 3 whereby the lead screw may be moved endwise in either direction by a corresponding movement of the adjusting nut 3. The lead screw 40 2 is suitably secured within this nut 3 against independent endwise or axial movement by meansl ofjthe lock nut 5 and the shoulder .t of the adjusting nut 3 but is permitted to rotate freely therein by means of the bearings i.

' Rotation of the lead screw is derived from a gear 'i which is constructed to have a sliding mesh with the usual change gears for dififerent R. P. M. of the lead screw and these gears are driven by the usual ydriving mechanism, which 50 it is not deemed necessary to describe herein.

Thus, it will be seen that instead of the usual means ,for positioning the lead screw within the frame of the machine, I have devised a means of oatingly securingthe lead screw within the 5| frame and fixed it to an axially movable member which is, in the present instance, moved axially by rotation hereinafter described although other moans may be provided for axially moving the lead screw without departing from the spirit of the present invention.

roller is guided in a groove II of a guide or cam slide I2 which, in turn, is carried by a bracket i I 5 secured to the machine. i

The cam slide I2 is slidably carried bya suitable member I2 rotatably secured to the bracket I5 by means of a pilot I6 which is held in place by a screw I1 and nut I8.

of suitable adjusting screws I3 and I4.

. Adjustment-of the slide I2` by means oi the adjusting nuts I3 and I4 thus rotates the pilot I6 onits screwpivot I'I to `any desired angle of the'slide I2 and thereby the cam slot II relative to the bracket I5.`

The nut 3 meshes with a threaded sleeve 20 held in xed .position on the frame 2| of the machine by means of any suitable holding means such as the screw 22.

When the lead screw 2 rotates, the slide or carrier 25 carrying the tools or work as the case may be is advanced by means of the usual nut engaging the lead screw and this slide 25is connected, in the present instance, with the cam slide I 2 by any suitable means such as the bracket 24 although it might` also be connected to the lead screw in the same manner as the slide 25, or in any other way adapted to travel during the operation of the tools on the work. Thus,` in the present instance, the cam slide will move with the work or tool slide in the same direction and the same distance.

It will be noted that this adjustment means comprises a train of parts operatively connecting the lead screw with its axially movable holding means for moving the holdingl means during the operation of the lead screw.

As the cam slide advances the angular setting thereof willcause the roller 9 traveling along the cam slot II to rotate the armi 8 and thereby the nut 3. It will be noted that the rotation is gradual and constant due to the shape of the slot II. This rotation of the nut 3 causes endwise movement thereof relative to the body or frame 2| and since the lead screw is positioned within the frame by means of this nut 3 it will, therefore, be moved axially during the operation of the tools upon the work. In other words, the lead will be retarded or advanced in accordance with the direction of inclination of the cam slide I2 and the advance lor retardation will be effective throughout the travel of the carrier. Where no adjustment of the lead screw is desired, the slide I2 may either be set straight or disconnected.

It will be seen that if the lead screw is ground accurately within .001" per foot in lead and it is required that the thread which is to be cut with the threading tool attached to the tool slide and controlled by this lead screw has to be .002" or .003" plus or minus of the'lead, this can be accomplished by this automatically adjustable nut 3 since vby adjusting the slide I2Vas many thousandthsiof an inch as desiredithe lead screw will bejsadvanced or retarded by -a forward or shapeof the slot II in the slide I2.

This pilot I6 is prol vided with micrometer graduations I9 and, to-V gether with the cam slide- I2, is adjusted by means backward movement in accordance with this adjustment of theslide I 2 and this movement of the lead screw willa be gradual and eiective throughout the length of the work.

In cases where it might be desired to cut a thread with the lead advanced at the beginning of the work and retarded at the end ofthe work, this is accomplished by merely changing'the In this case, the slot would be either V-shaped or oval and, similarly, any other variation in lead may be accomplished by a slight variation in the shape of the slot II to correspond with the desired change in lead desired.

It is to be understood that, by describing in detail herein any particular form, structure or arrangement, it is not intended to limit the, invention beyond the terms of the several/claims or the requirements of the prior art.

Having thus explained the nature of my said invention and described a way of constructing andusing the same, although without attempting to set forth all of the forms in which it may be made or all of the modes of its use, I claim:

1. In a machine, the combination of a oatingly supported lead screw, means for rotating it, a carrier fed by the lead screw and into which said lead screw extends, and means for axially adjusting the lead screw during the feeding of said carrier, said adjusting means constantly increasing the axial movement of said lead screw in a single direction.

2. In a machine, the combination of a oatingly supported lead "screw, means for rotating it, a carrier axially movable with and relative to the lead screwby said lead screw, and` means for axially adjusting the lead screw during the feeding of said carrier to move the carrier with the lead screw,said adjusting means constantly increasing the axial movement of said lead screw in a single direction. I

3. A machine having a'lead screw, means for rotating it, a holding member therefor having` a threaded connection with a xed part of said machine, a carrier having a threaded engagement with the lead screw for shifting said carrier axially thereof, a member movable with 'said carrier, and a connecting member rigidly connected with the rholding member and cooperating with the movable member whereby on the movement of said movable member the holding member will be rotated in the machine to shift the lead screw and said carrier axially independently of their threaded engagement.

4. A machine having a rotatable and-axially movable member carried by a stationary portion -of said machine, a rotatable lead screw carried pendently of their relative axial shifting.

5. A machine of the class described having a rotatable and axially movable member carried by a stationary portion of -the machine, a. rotatable lead screw carried by said movable member for axial movement therewith and having iioating connection with the machine, a carrier movable with and relative to said lead screw, means for rotating the lead screw to eifect said relative movement of the carrier. a member shift-` able with the carrier, and a connecting member rigidly connected with said axially movable member and cooperating with said shiftablev member whereby on the movement of the shiftable member the ymovable member will be rotated to shift the lead screw and carrier axially independently of their relative axialv shifting.

6. A machine of the class described having a rotatable and axially movable member carried by a stationary portion of the machine, a rotatable lead screwA carried by said movable member for axial movement therewith and having floating connection with Ythe machine, a carrier movable with and relative to said lead screw, means for rotating the lead screw to eect said relative movement ofV the carrier, a member shiftable' with-the carrier, and a connecting member rigidly connected with said axially movable member and' cooperating with said shiftable member whereby on the movement of the shiftable member the movable member will be rotated to shift the lead screw and carrier axially indevpendently of their relative axial shifting, said able with the carrier, a connecting member rigidly connected with said axially movable memt ber and cooperating with said shiftable member whereby on the movement of the shiftable meinber the movable member will be rotated to shift the lead screw and carrier'axially independently 'of their relative axial shifting, said shiftable 'member and connecting member having interlead screw connected therewith for shifting said carrierl relative to the lead screw, shiftable means carried by a stationary part of the machine, said lead screw oatingly supported relative to the machine and carrledby said shiitable means, a slide having a cam and movable with the carrier, and a swinging arm cooperating with the cam and with the lead screw through the shiftable means for vshifting the lead screw and carrier together. l

- 9. A'machine having a shiftable carrier, a lead screw connected therewith for shifting said carrier relative to the lead screw, shiftable means carried by a stationary part of the machine, said lead screw oatingly supported relative to the machine and carried by said shiftable means, an adjustable and pivoted slide having a camand movable with the carrier, and a swinging arm cooperating with the `cam and with the lead screw through the shiftable means for shiftingV the lead screw and carrier together, 

